whoops (was: no subject!)
- I wrote (nonsensically):
> Then you should test gcd(a^N-1 mod N,N) and gcd(b^N-1 mod N,N).This was rubbish, sorry. The new online reply facility is
> Then nothing new would be learnt from gcd(a^N-1 mod N,b^N-1 mod N).
seductive; must learn to think before I type!
I was mentally confusing this idea of Pavlos with
Marcel Martin's cunning way of factorizing pseudoprime
composites, which uses gcd(a^u-b^u mod N,N),
with u dividing N-1, as I recall.